I'd forgotten about that bit about some animals going on the ark in sevens, and certainly could not have remembered which ones. (How does one determine that a species that was in fact unknown to the Hebrews would have been unclean, BTW?)

If I wanted to play with this story as many would do with Tolkien (which has the virtue of being far more entertaining--it's amazing how hum drum the Hebrew mythos is compared to many others), I'd wonder what the sex ratio was in those groups of seven. Clearly for animals that tend to have an alpha male and a harem of women (like deer, walruses or gorillas, but I don't know if they are unclean or not), you'd want a 1:6 ratio for rapid regeneration of the species, but penguins pair 1:1 and both are vital for reproduction even after fertilization. So you'll likely end with a 3:4 or 4:3 ratio and one of the seven is a spare, I guess, or has to wait for one of the offspring to become mature, it's be a "May/December" mating (though in the southern hemisphere perhaps that's best put "November/June").

No no no. Not if he could drop them off at Gondwanaland. You see, the breaking up of Gondwanaland and the migration of the continents to their current positions happened after Noah, probably about 4500 years ago. ;)

I think you should also keep in mind that many cultures have similar depictions and myths about dragons or great serpents. We can easily say that fire-breathing, mythological dragons weren't real due to a lack of evidence for them.

For whatever reason, all those cultures have similar myths even if they've never had contact with each other. That could be the same thing here: many cultures having some myths with common features. It doesn't imply a connection. They could be related to events that they all experience (being around bodies of water) or simply be related to the cultural importance of the myth (the body of water, etc.).

It's pretty simple and that last part is, I would say, correct. Any culture that lives in a flood plain will experience terrible floods that threaten to sweep away (or actually sweep away) their people. Considering that almost all of humanity is settled along waterways, a consistent source of freshwater being necessary to the growth of a population, it should really come as no surprise that there is a shared history of myths about surviving floods.

I don't know that there's a scientific connection. I think it's more that there is a common sense connection.

It makes historical sense in the ways civilizations sprang up, fell apart, and rebuilt. Though as some one who appreciates literature, it can make for a really great epic story. I've actually thought about reading through Genesis and creating an epic tale out of what it offers - especially where the details are obscure.